Thermal characteristics of mountain lion dens

We used radiotelemetry and searched with a trained hound to locate the dens of 3 recently parturient mountain lions (Felis concolor). These dens were located in dense riparian vegetation along the same stream in the bottom of a steep canyon. We monitored the circadian temperatures of 2 dens at 1-h intervals and compared them to ambient temperatures recorded simultaneously. We found mountain lion dens to effectively moderate high ambient temperatures, but these dens failed to provide a thermal advantage at the lowest ambient temperatures recorded in this investigation. We conclude that mountain lion dens provide effective protection from thermal maxima for young, immobile kittens.